The precursor of Alzheimer's disease amyloid A4 protein resembles a cell-surface receptor

Alzheimer's disease is characterized by a widespread functional disturbance of the human brain. Fibrillar amyloid proteins are deposited inside neurons as neurofibrillary tangles and extracellularly as amyloid plaque cores and in blood vessels. The major protein subunit (A4) of the amyloid fibril of tangles, plaques and blood vessel deposits is an insoluble, highly aggregating small polypeptide of relative molecular mass 4,500. The same polypeptide is also deposited in the brains of aged individuals with trisomy 21 (Down's syndrome). We have argued previously that the A4 protein is of neuronal origin and is the cleavage product of a larger precursor protein. To identify this precursor, we have now isolated and sequenced an apparently full-length complementary DNA clone coding for the A4 polypeptide. The predicted precursor consists of 695 residues and contains features characteristic of glycosylated cell-surface receptors. This sequence, together with the localization of its gene on chromosome 21, suggests that the cerebral amyloid deposited in Alzheimer's disease and aged Down's syndrome is caused by aberrant catabolism of a cell-surface receptor.

A highly sensitive immunoenzymometric assay involving "common-capture" particles and membrane filtration

This highly sensitive immunoenzymometric method involves monoclonal antibodies, a common-capture microsphere, and a rapid, membrane-filtration separation step. The common-capture solid phase is monoclonal anti-fluorescein antibody convalently attached to 6.5 micron-diameter latex particles. In sandwich-type assays for large-molecule analytes, the capture antibody is conjugated with fluorescein isothiocyanate and the probe antibody is conjugated with beta-galactosidase (EC 3.2.1.23). In competitive assays for small analytes, the analyte-beta-galactosidase conjugate competes with the analyte in the clinical samples for the fluoresceinated capture antibody. After simultaneous incubation of the reagents for 2 h, the bound and unbound reagents are separated by filtration through the bottom of each well of a 96-well plate. Substrate (4-methylumbelliferyl-beta-D-galactopyranoside) is then added to the wells, and the rate of product formation is determined kinetically for 12 min. The rate is proportional to the concentration of analyte in the sandwich assays and inversely proportional in the competitive assays. The assay results for choriogonadotropin, thyrotropin, digoxin, and thyroxin show the assay to be sensitive, rapid, and applicable to any size analyte. With this system, several different sandwich and (or) competitive-type assays can be performed simultaneously on the same plate.

A highly sensitive immunoenzymometric assay involving "common-capture" particles and membrane filtration

This highly sensitive immunoenzymometric method involves monoclonal antibodies, a common-capture microsphere, and a rapid, membrane-filtration separation step. The common-capture solid phase is monoclonal anti-fluorescein antibody convalently attached to 6.5 micron-diameter latex particles. In sandwich-type assays for large-molecule analytes, the capture antibody is conjugated with fluorescein isothiocyanate and the probe antibody is conjugated with beta-galactosidase (EC 3.2.1.23). In competitive assays for small analytes, the analyte-beta-galactosidase conjugate competes with the analyte in the clinical samples for the fluoresceinated capture antibody. After simultaneous incubation of the reagents for 2 h, the bound and unbound reagents are separated by filtration through the bottom of each well of a 96-well plate. Substrate (4-methylumbelliferyl-beta-D-galactopyranoside) is then added to the wells, and the rate of product formation is determined kinetically for 12 min. The rate is proportional to the concentration of analyte in the sandwich assays and inversely proportional in the competitive assays. The assay results for choriogonadotropin, thyrotropin, digoxin, and thyroxin show the assay to be sensitive, rapid, and applicable to any size analyte. With this system, several different sandwich and (or) competitive-type assays can be performed simultaneously on the same plate.

Improvements in dehydration and cement line staining for methacrylate embedded human bone biopsies

Undemineralized methacrylate embedded bone biopsies and other bone specimens can be processed much more rapidly by application of acidified 2,2-dimethoxypropane (DMP) dehydration, which requires two hours, than by traditional graded ethanol dehydration, which requires at least four days. This shortened processing time is valuable when biopsy results are urgently needed to detect osteomalacia or to determine bone features prior to possible parathyroidectomy. We have processed over 200 bone specimens with DMP and have compared DMP dehydration to graded ethanol dehydration in 11 biopsies in which two plugs were available from the same patient. DMP dehydration does not compromise the following: tetracycline retention, Goldner's stain, acid phosphatase localization or histochemical identification of aluminum. Cement lines, which provide a record of past remodelling, are useful in clinical interpretation of bone biopsies. We have adapted two stains, toluidine blue and methylene blue/basic fuchsin, for improved cement line identification. Five-micrometer sections individually demineralized in acetate buffer prior to cement line staining show best results with toluidine blue at pH 5.5 and with methylene blue/basic fuchsin at pH 2.5-3.5.

Metabolic basis of improved exercise tolerance: muscle phosphorylase deficiency after glucagon administration

A 26-year-old girl with muscle phosphorylase deficiency had exercise intolerance and experienced an occasional "second wind" phenomenon. Muscle glycogen concentration was about three times the normal level, whereas each glycolytic intermediate below the phosphorylase step was equivalent to only 10% of a normal level. Semi-ischemic forearm exercise tests disclosed no elevation of the venous lactate or pyruvate level, but they showed remarkable increases of serum creatine kinase and ammonia. Glucagon administration markedly augmented exercise tolerance. Forearm exercise after glucagon injection significantly increased venous lactate. Thus, the beneficial effect of glucagon is attributable to blood glucose utilization by muscle.

Thyrotoxic myopathy associated with subacute thyroiditis

We report a case of subacute thyroiditis complicated by thyrotoxic myopathy. Previously thyrotoxic myopathy has been described as being associated with Graves' disease. The patient in this study was a 35-year-old man who developed proximal dominant muscular weakness and atrophy during the course of subacute thyroiditis. His myopathic symptoms regressed as his serum thyroxine and triiodothyronine levels returned to normal, however it took a relatively long period of time for them to do so. This suggests that marked myopathy may develop even in cases of subacute thyroiditis if the thyrotoxic state persists for a long period of time.

The Guillain-Barré syndrome: clinical and electroneuromyographic studies

Clinical and electrophysiological studies were carried out on 39 patients with the Guillain-Barré syndrome to evaluate which elements were of prognostic value during the acute phase. Residual clinical signs such as motor weakness and absent patellar tendon reflexes were found in 16 (52%) of those patients who had had a preceding illness. Persistence of deficit was significantly correlated to age at onset, the degree of quadriparesis and loss of deep sensation in the acute phase. Of the 10 patients who showed a reduction in motor nerve conduction velocity (MCV) in the early stage, 8 (80%) revealed significantly residual clinical symptoms at follow-up. There was a tendency for the incidence of residual signs to be more common in the patients with slowing of mixed nerve conduction velocity, and prolonged latency of H-wave and the residual latency. Nerve conduction studies, especially measurement of MCV, were of value as a reliable prognostic indicator in this syndrome.

Radioimmunoassay for antibodies to human skeletal muscle myosin in serum from patients with polymyositis

Antibodies to human skeletal muscle myosin were detected in 90% of sera from patients with polymyositis by radioimmunoassay using purified human myosin as antigen, and the mean titre was 4.24 X 10(-10)M. The incidence and the mean titre of anti-myosin antibodies were significantly higher than in patients without polymyositis. Anti-myosin antibody titres correlated with steroid therapy in polymyositis patients. Titres in untreated patients with polymyositis correlated with the severity of muscle weakness. Radioimmunoassay for anti-myosin antibodies should prove to be useful in the diagnosis of polymyositis and the evaluation of clinical state.

Serum mitochondrial aspartate aminotransferase in patients with polymyositis

The clinical significance of serum aspartate aminotransferase (GOT) isozymes was studied in 18 patients with polymyositis. Abnormally high levels of mitochondrial GOT (mGOT) (6.2 +/- 1.2 IU/L, mean +/- SEM; normal, less than 2.0 IU/L) and cytosol GOT (sGOT) (95 +/- 21.6 IU/L; normal, less than 25 IU/L) were observed in sera. In polymyositic muscles, the sGOT level was significantly decreased but mGOT was not. The levels of serum sGOT and mGOT and the ratio of mGOT/tGOT before corticosteroid therapy correlated well with the severity of muscle weakness. Serial determination of CPK, sGOT, and mGOT during corticosteroid therapy revealed that mGOT most rapidly returned to normal. Exercise did not increase serum mGOT in polymyositis.

Acetylcholine receptor and thymus in experimental autoimmune myasthenia gravis and experimental myositis

This study was attempted to obtain information about biological properties of junctional acetylcholine receptor (AChR) and extrajunctional AChR, and about nerve influences on muscles AChRs under the pathological conditions of experimental myasthenia and myositis. Experimental autoimmune myasthenia gravis (EAMG) was induced in Wistar rats by immunizations with AChR purified from the electric organ of Narke Japonica without using Freund's complete adjuvant experimental myositis by immunization with rat muscle extract depleted of AChR. Thirty-five days after the initial immunization, unilateral dissection of the ischiadic nerve was performed in all immunized rats. Contents of AChR in both hind limb muscles were measured by double immunoprecipitation assay method 15 days after the experimental denervation. In the control animals the amount of AChR extractable from innervated muscles was 2.7 +/- 0.5 (mean +/- s.d.) pmole/g muscle and increased about 10-fold 15 days after the denervation (30 +/- 7.9). In rats with EAMG, AChR contents was reduced in both denervated (1.1 +/- 1.0) and innervated muscles (1.3 +/- 0.9). In experimental myositis, the increase of muscle AChR was impaired in denervated muscles (2.4 +/- 0.6), but AChR contents was not reduced in innervated muscles (2.7 +/- 0.9). These results suggest that nerves may influence AChR metabolism, keeping numbers of AChR constant even in inflammatory condition. In addition, germinal centre formation in thymic medulla was detected in EAMG rats.

A model of focal cortical contusion in gerbils

An experimental model of focal laceration and contusion in gerbils is described. Associated with this injury are systemic changes which are neurogenically mediated and result in an immediate reduction in blood pressure, bradycardia, and generalized reduction in cerebral blood flow. There is generalized edema, as judged by a decreased specific gravity in the brain, probably related to reduced blood flow; superimposed on this, there is an edema gradient which is maximal close to the injury. This, in turn, affects the local capillary bed and prevents any local increase in flow. A separate group studied over a longer time period (6 hours) did not reveal egress of Evans blue into the surrounding tissue and this is in contrast to reports from cold-injury studies.

Generation and chracterization of variants of mouse hepatoma cells with defects in hepato-specific gene expression. I. Albumin synthesis variants

Clonal variants of mouse hepatoma cells that either fail to produce albumin (variant 19/2) or show significantly reduced levels (100-fold less) of albumin production (variant 1/c/1) were isolated from the parental line. Hepa la, after a single exposure to N-methyl-N'-nitrosoguanidine (MNNG). Intracellular levels of albumin in both variants were below detection by our assay. Analyses by cDNA-RNA reassociation kinetics indicate that there are approximately 3900 molecules of cytoplasmic albumin mRNA per cell in the parent and less than 10 molecules per cell in both variants. Southern blotting of the Eco RI restriction fragments of cellular DNA from the parent and variants did not indicate any major deletions in the albumin gene DNA sequences. We conclude that in the two variants studied, processes that regulate albumin production via alterations in the level of cytoplasmic albumin mRNA have been affected. Our analyses have also shown that alpha-fetoprotein (AFP) production is lacking in one variant (19/2) and is slightly reduced in the other (1/c/1). Transferrin secretion is lower than the parental line in both variants. Thus multiple nonlethal defects in hepatic gene expression can be obtained in Hepa la cells in culture that will be useful in determining the number and kinds of genes that control the expression of liver-specific loci.

Clinical features, investigation and treatment of post-traumatic syringomyelia

Thirteen patients who sustained spinal cord trauma causing persisting disability, developed new symptoms, the chief one of which was severe pain unrelieved by analgesics. The clinical diagnosis of post traumatic syringomyelia was confirmed in each case by means of myelography, as well as endomyelography in seven patients. In every case exploration of the spinal cord syrinx was performed. Ten patients were troubled by severe pain while three patients were mainly subject to altered sensation in the upper limbs. Of the six patients who had initially sustained complete cord transections, three were treated by cord transection and three were treated by syringostomy. The seven patients who sustained incomplete cord lesions were all treated by syringostomy. The patients who initially sustained incomplete sensory motor spinal cord damage had a better symptomatic response to surgery than hose who had sustained a complete spinal cord lesion. The ten patients whose main symptom was severe pain were completely relieved of their symptoms by surgery.

Specificities of antibody to acetylcholine receptor in rabbits with experimental myasthenia gravis

The injection of acetylcholine receptor (AChR) purified from Narke electroplax japonica induced 'experimental autoimmune myasthenia gravis' (EAMG) in rabbits. Serial measurements of anti-AChR antibody titre using Narke AChR and rabbit AChR as antigen revealed that the intensity of myasthenia had a rather closer correlation with titre to Narke AChR than that to rabbit AChR. Antibody reacting to rabbit AChR was almost completely adsorbed out with torpedo receptor conjugated to agarose. Serum concentrations of antibody protein measured by affinity chromatography ranged from 54 to 896 microgram/ml serum and were well correlated with the intensity of myasthenia. The results suggested that in rabbits immunized with heterologous AChR the cross-reaction of anti-heterologous AChR antibody with rabbit AChR caused myasthenia rather than an immune response specific to rabbit AChR dose.

Ethambutol neurophathy: clinical and electroneuromyographic studies

Clinical features including changes in the peripheral nerve conduction were analzyed in 10 cases with ethambutol neuropathy. There were abnormalities in the visual field in seven and optic atrophy in five of 10 cases. Seven of 10 cases complained of numbness in the lower limbs. The age of onset and dose of ethambutol the patients continue to take after the occurrence of visual impairment were found to be important in determining the severity of neurological symptoms. A functional disturbance was more conspicuous in ethambutol neuropathy, particularly in the sensory system than in the motor system so far as the peripheral nerve conduction was serially examined. Some cases still had serious optic disturbances even about seven years after the onset of the disease and the presence of irreversible lesions was suspected.

Chromatin assembly in isolated mammalian nuclei

Cellular DNA replication was stimulated in confluent monolayers of CV-1 monkey kidney cells following infection with SV40. Nuclei were isolated from CV-1 cells labeled with [3H]thymidine and then incubated in the presence of [alpha-32P]deoxyribonucleoside triphosphates under conditions that support DNA replication. To determine whether or not the cellular DNA synthesized in vitro was assembled into nucleosomes the DNA was digested in situ with either micrococcal nuclease or pancreatic DNase I, and the products were examined by electrophoretic and sedimentation analysis. The distribution of DNA fragment lengths on agarose gels following micrococcal nuclease digestion was more heterogeneous for newly replicated than for the bulk of the DNA. Nonetheless, the state of cellular DNA synthesized in vitro (32P-labeled) was found to be identical with that of the DNA in the bulk of the chromatin (3H-labeled) by the following criteria: (i) The extent of protection against digestion by micrococcal nuclease of DNase I. (ii) The size of the nucleosomes (180 base pairs) and core particles (145 base pairs). (iii) The number and sizes of DNA fragments produced by micrococcal nuclease in a limit digest. (iv) The sedimentation behavior on neutral sucrose gradients of nucleoprotein particles released by micrococcal nuclease. (v) The number and sizes of DNA fragments produced by DNase I digestion. These results demonstrate that cellular DNA replicated in isolated nuclei is organized into typical nucleosomes. Consequently, subcellular systems can be used to study the relationship between DNA replication and the assembly of chromatin under physiological conditions.